package com.ruoyi.common.utils;

import org.apache.commons.codec.binary.Base32;
import org.apache.commons.codec.binary.Base64;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

/**
 * 校验器工具类
 */
public class GoogleCodeUtil {

    // 生成的key长度( Generate secret key length)
    public static final int SECRET_SIZE = 10;

    public static final String SEED = "22150146801713967E8g";
    // Java实现随机数算法
    public static final String RANDOM_NUMBER_ALGORITHM = "SHA1PRNG";
    // 最多可偏移的时间
    public static final int window_size = 3; // default 3 - max 17

    public static String createSecretKey ( ) {
        SecureRandom sr = null;
        try {
            sr = SecureRandom.getInstance ( RANDOM_NUMBER_ALGORITHM );
            sr.setSeed ( Base64.decodeBase64 ( SEED ) );
            byte[] buffer = sr.generateSeed ( SECRET_SIZE );
            Base32 codec = new Base32();
            byte[] bEncodedKey = codec.encode ( buffer );
            String encodedKey = new String ( bEncodedKey );
            return encodedKey;
        } catch (NoSuchAlgorithmException e) {
            // should never occur... configuration error
        }
        return null;
    }

    /**
     * 这个format不可以修改，身份验证器无法识别二维码
     *
     * @param tag
     * @param secret
     * @return
     */
    public static String createOtpauth ( String tag , String secret ) {
        String format = "otpauth://totp/%s?secret=%s";
        return String.format ( format , tag , secret );
    }

    public static boolean check_code ( String secret , String code , long timeMsec ) {
        Base32 codec = new Base32();
        byte[] decodedKey = codec.decode ( secret );
        // convert unix msec time into a 30 second "window"
        // this is per the TOTP spec (see the RFC for details)
        long t = (timeMsec / 1000L) / 30L;
        // Window is used to check codes generated in the near past.
        // You can use this value to tune how far you're willing to go.
        for (int i = -window_size; i <= window_size; ++i) {
            long hash;
            try {
                hash = verify_code ( decodedKey , t + i );
            } catch (Exception e) {
                // Yes, this is bad form - but
                // the exceptions thrown would be rare and a static
                // configuration problem
                e.printStackTrace ();
                throw new RuntimeException ( e.getMessage () );
                // return false;
            }
//            System.out.println ( "code=" + code );
//            System.out.println ( "hash=" + hash );
            if (code.equals ( addZero ( hash ) )) {
                return true;
            }
/*            if (code==hash ) {
                return true;
            }*/
        }
        // The validation code is invalid.
        return false;
    }

    private static int verify_code ( byte[] key , long t ) throws NoSuchAlgorithmException, InvalidKeyException {
        byte[] data = new byte[8];
        long value = t;
        for (int i = 8; i-- > 0; value >>>= 8) {
            data[i] = (byte) value;
        }
        SecretKeySpec signKey = new SecretKeySpec ( key , "HmacSHA1" );
        Mac mac = Mac.getInstance ( "HmacSHA1" );
        mac.init ( signKey );
        byte[] hash = mac.doFinal ( data );
        int offset = hash[20 - 1] & 0xF;
        // We're using a long because Java hasn't got unsigned int.
        long truncatedHash = 0;
        for (int i = 0; i < 4; ++i) {
            truncatedHash <<= 8;
            // We are dealing with signed bytes:
            // we just keep the first byte.
            truncatedHash |= (hash[offset + i] & 0xFF);
        }
        truncatedHash &= 0x7FFFFFFF;
        truncatedHash %= 1000000;
        return (int) truncatedHash;
    }

    private static String addZero ( long code ) {
        return String.format ( "%06d",code );
    }

    // 验证方法，code是app上的动态码，key是在二维码生成后获得的
    public static boolean ValidCode(String code,String key){
        long time = System.currentTimeMillis ();
        boolean result = check_code ( key,code,time );
        return result;
    }
}
